/Engine/Plugins/FX/NiagaraSimCaching/Source/NiagaraSimCachingEditor/Public/Sequencer/MovieSceneNiagaraTrackRecorder.h
Particle Systems are entire components and you can't animate them as a property.
virtual bool CanRecordProperty ( class [UObject](API\Runtime\CoreUObject\UObject\UObject) * InObjectToRecord, class [FProperty](API\Runtime\CoreUObject\UObject\FProperty) * InPropertyToRecord ) const